On Thu, 4 Jun 2009, Robert Haas wrote:
> That's because this thread has altogether too much theory and
> altogether too little gprof.
But running benchmarks and profiling is actual work; that's so much less
fun than just speculating about what's going on!
This thread reminds me of Jignesh's "Proposal of tunable fix for
scalability of 8.4" thread from March, except with only a fraction of the
real-world detail. There are multiple high-profile locks causing
scalability concerns at quadruple digit high user counts in the PostgreSQL
code base, finding them is easy. Shoot, I know exactly where a couple
are, and I didn't have to think about it at all--just talked with Jignesh
a couple of times, led me right to them. Fixing them without causing
regressions in low client count cases, now that's the hard part. No
amount of theoretical discussion advances that any until you're at least
staring at a very specific locking problem you've already characterized
extensively via profiling. And even then, profiling trumps theory every
time. This is why I stay out of these discussions and work on boring
benchmark tools instead.
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD